Tunnel kiln



T. TALBOT TUNNEL KILN May l2, 1931.

Filed July 22, 1929 2 Sheets-Sheet 1 INVENTOR. 77/oM/1 ATTORNEYS.

Patented May 12, 1931 f UNITED .SIA-res rar1:Nr" OFFICE TIatOIvIAsk TALBOT, or SEDGLEY, NEAR DUDLEY, WORoEsTnR, ENGLAND, AssIGNoIa BY MnsNE ASSIGNMENTS, To swINnnLL-Dnnssnnn CORPORATION, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION or PENNSYLVANIA TUNNEL KILN Application. led July 22,

My present invention relates in general to the construction and method of operation of continuous tunnel kilns of the type in which ,the cooling Zone and effectively utilizing the heat abstracted for preheating air for combustion of the fuel in the heating zone and other purposes. Another object of my invention is to provide an improved arrangement and locationof the fan mechanism, for circulating the cooling medium, Vwhich is preferably air drawn from Ythe surrounding atmosphere. A further object of my invention is to provide an improved kiln constructionand apparatus for maintaining predeterminedthermal conditions in the cooling Zone, and particularly in the portion of the cooling zone adjacent the heatingzone.

The various features of4 novelty which characterize my invention are pointed out with particularity in the claims annexed to andforming a part of this specification. For a better understanding of the invention, however, and the advantages possessed byit reference should be had to the accompanying drawings and descriptive matter in which l have illustrated-and described a preferret embodiment ofthe invention.

Of the drawings: v Fig. 1 is a somewhat diagrammatic longitudinal elevation with parts broken away and in section of a portion of a kiln;

Fig. 2 is a plan view of the apparatus illustrated in Fig. l with parts broken away;

. Fig. 3 is a transverse section on the line 3*-8; and

Fig. 4 is a similar section on Vthe line 4-4 of Fig. l.

In `the drawings I have illustrated the use 1929. serial No. 379,973.

of my Vinvention in a'ftunnel kiln of a welll known type but having certain special features of construction due to ythe use therein of the presentinvention As shown, the kiln comprises ahorizontally elongated kiln chamber A enclosed by vertical side walls B of refractorymasonry and insulated in any of the usual ways. The kiln is formed with the usual masonry benches Cr extending through- ,out the kiln chamberV and located at opposite sides of the goods pathway.vvv Kilns of this type comprise a heating or furnace zone a and a coolingvzone Z9 through-which the goods to be treated are carried on cars which enter the kiln at the yinlet end of the heating Zone and p ass successively through the heating and cooling Zones, and are removed from the exit end of the latter. Y rlhe inlet and exit ends of the kiln are provided with means permitting the insertion and removal, respectively, of the kiln carswithout any appreciable entrance of air into, or escape of heating gases from, t-he kiln chamber. y

In the heating zone, the kiln heating means may consist of elongated combustion chambers-or muflles, fireboXes, or groups of gas oroil burners. While the specific form of heating means used forms no part of my present invention, I have illustrated a fuel supply conduit D having branch pipes D leading to` groups ofvfuel burners mounted in the sidewalls B in the heating Zone.

rlhe cooling zone Z9 is divided into a'short initial or high temperature section b having the same external width as the heating zone and a main or low temperature section b2 between the initial section o and the eXit end of the kiln. The main section has a kiln chamber width similar to that in the initial section but side walls of considerably less thickness vthan-the latter, as shown in Figs. 3 andt. ,As illustrated in Figs. 1 to 3, the cooling zone section b2 is constructed with a hollow arch consisting of vertical wall secterial spaced from the wall sections F and the kiln crown'A, sniiiciently to form side and crown cavities H and J, respectively, therebetween. The crown cavity J opens at its sides to the side cavities H. The side wall sections F are slightly spaced from the main side walls B and the space therebetween preferably filled with insulating material. The wall sections F are connected to the sides of the wall G by tie bricks E at spaced points, as shown in Fig. 3. Y

The wall cavity at each side ofthe section b2 is divided into a series of end to end compartments H, H2, H2, H4 by division walls K extending vertically between the correspond ing arched wall G and the adjacent wall section F. The division walls extend across the kiln crowndividing the crown cavity into a similar series of crown compartments J J2, J2 .Reach of which is connected to corresponding side cavities H, H2, etc. As shown in Fig. 2, the division walls K` are provided with expansion oints K to allow relative expansion andcontraction-l of adjoining arch vsections underV varying thermal conditions. Each of the side vcompartn'ients H', H2, etc. lare connected at their lower ends to a horizontal distributing iue M2 by passages M3. The flues M2 open to the external atmosphere through one or more air inlet ports M controlled by dampers M, the number and size of the ports depending on the estimated amount of cooling medium required. Each Vof the corresponding crowncompartments is connected with a vertical outlet pipe N mounted in the kiln crown adjacent the division wall at the inlet end ofthe compartment. Each pipe N opens into an air collector pipe or masonry flue N extending longitudinally of the kiln above the kiln crown.

The cooling zonev section b is provided with a hollow arch formed by an inner arched wall P of panel brick, of carborundum or other material of high thermal conductivity, spaced from the innerlface of the side wall B and kiln crown A and' mounted on the kiln benches C as heretofore described. Each of the side wall cavities in this section of the cooling zone isV divided into a plurality of relatively narrow vertical channels Q by projecting portions B of the'kilnside walls. The crown cavity Q in this section of the kiln is similar to those in the section b2 and connects lthe various side channels Q with l'an inlet pipe Q2 mounted in the kiln crown. The channels Q open at their lower end s into the longitudinally ext-ending ducts R located below the side walls. The ducts R extend below the heating zone ofthe kiln and are connected to the various groups of fuel burners in a manner well known in the art.

yThe collecting pipe N, which extends Yabove the cooling zone section b2, is closed at its end adjacent the exit end of the kiln and its opposite end connected to the inlet 4side of a cooling fan S driven by an electric pipe N is controlled by a damper S2 positioned in the pipe N adjacent the fan. The

fan discharge is connected to a main discharge pipe T to which the inlet pipe Q2 leading to the crown cavity Q in the cooling zone section b is connected. The fan discharge pipe is also provided with branch pipes T and T2, the pipe T opening to the `atmosphere or preferably to a drying or preheating chamber adjacent to or forming a part of the kiln illustrated, and the pipe T2 being'connected as shown to one or more nozzles T3 immediately beneath the crown portion of the` wall G and through which the air is discharged into the kiln chamber to off-set the tendency of the hot gases in the kiln chamber to drift toward the exit end of the kiln chamber. The air discharged into the kiln chamber, at this point may travel longitudinally of the kiln chamber to the entrance end there` of or may be withdrawn into the cooling zone cavities through port T5 in the wall G,

as illustrated diagrammatically in Fig. 1.

Each of the pipes T, T and T2 connected to the fan discharge is provided with a damper T4, whereby the amount. of air therethrough may be regulated.

In operation the goods carrying cars are periodically inserted into the kiln one at a time and as each car is thus inserted, the train of cars filling the kiln chamber is moved forward a car length, a car being removed from the cooling zone of the kiln each time a car is inserted at the entrance end of the kiln. As a car moves slowly through the heating zone of the kiln, the goods are gradually heated up to their maximum temperature and as each car passes through the cooling zone, the sensible heat in the goods and in the car is to a large extenttransferred to the adjacent walls P and G, fromV which the heat is taken up by the large volume of low temperature circulating cooling air passing upwardly through the cavity compartments H', etc.. formed at the sides of the goods pathway. The Iair heated in each'compartment passes along through the corresponding crown compartment where more heat is absorbed and through the outlet pipe -N to the hot air collecting pipe N. The air from each compartment is thus drawn to the air fan S. In normal operation only a small portion of the air necessary for cooling purposes is utilized for combustion, the fan discharging this portion of the air through the pipe Q2 to the crown cavity Q. The air for combustion is further heated to a relatively high temperature while passing horizontally through the crown cavity Q and downwardly through thenarrow side channels Q to the underground ducts R leading to the fuel burners. The main body of cooling air passing to the fan is discharged to the pipes T and T 2 and utilized for the purposes described. j y j With a. kiln constructed and operating as heretofore described, the pressure of the cooling air in the cooling zone section b2 is below atmospheric pressure, while the pressure of the air for combustion passing downwardly through the cooling zone section is advantageously above atmospheric pressure. The kiln chamber temperature descreases at a relatively rapid rate in the successive cooling zone sections due to the large volume of cooling air in circulation and the external radiation of the side walls. The coolingzone temperatures can be closely regulated by varying the speed of the fanand/or the effective inlet port area.

The heated air for combustion delivered to the ducts R may be at a temperaturev above 500 C. By my invention the fan is advan tageously positioned at a point where the temperature of the cooling air handled is well below the allowable temperature for safely operating the fan, but where it can detinuous crown cavity, the amount of air en tering each wall section being regulated by the dampers M. n

While in accordance with the provisions of the statutes, VI have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit of my invention as set forth in the appended claims and thaty in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

Having now described my invention what I claim as new and desire'to secure by Letters Patent, is

l. In a tunnel kiln comprising a heating zone and ya cooling zone with a goods passageway therethrough, the improvement which comprises a fluid channel adjacent said goods passageway in lone portion of the cooling zone, a second cooling zone portion between said first mentioned portion and said heating zone and means for circulating a coolv which comrrsesauidechanneladimentmd yseeds @assassina @ne ,Partien 0fA the ,aceline cena, secc-nd Regeling @eee `richtige 'be- .tfweaeaidmeneame Partien; endend y heating Zonaendfmeans; 011 Circulating wir ter' @embustem Ztlel?Quelle.aid channel insaid ret 4fm.entirered @erden at e Pressure below anmachen@ and delivering Said air t@v said ,Secondi-Irlandese@ rerton at a pressure above kiln comprising a heating means .for drawing air through said first mentioned channel and delivering said air under pressure to said last mentioned channel. t

4. In a tunnel kiln comprising a heating zone and a subsequent cooling zone with a goods passageway therethrough, the improvement which comprises means for heating air for combustion in said cooling zone and delivering said heated air to said heating zone,

said means comprising a circulating fan lo-.

cated at a point externally of said kiln and adjacent said heating and cooling zones.

5. In a tunnel kiln comprising a heating zone and a subsequent cooling zone with aV goods passagewaytherethrough, the improvement with comprises means dividing said cooling zone into adjacent high and low temperature sections and a circulating fan located intermediate said high and low temperature sections for circulating a cooling medium therethrough. y

6. A tunnel kiln having a heating zone, a

cooling zone, a goods passageway through f said zones, a plurality of separate compartments in the side walls of said cooling zone,

conduits connecting said compartments, a circulating fan arranged in said conduit connections for circulating a. cooling medium therethrough, conduits connected to the outlet of said fan, and means for separately delivering regulable portions of said cooling medium to the goods passageway in said cooling zone and to the fuel burners in said heating zone.

7. A tunnel kiln comprising a cooling zone, a goods passageway-through said zone, a Vseries of separate hollow arches is said zone partially enclosing said passageway, a conduit connecting said arches, and means for circulating a cooling medium upwardly through some of said arches and downwardly through another of said arches.

r8.V The method of operating a continuous n tunnel kiln having a cooling zone which consists passing a' coolingiiuid vat a sub-'atmospheric pressure through onev portion of said coolingzone and deylivering said cooling Huid to .another` portion of said cooling zone at super-atmospheric pressure.

9.7 The methodl of-op'erating a; continuous tunnelkiln having a heating zone anda e001- ing zoneV which consists in circulating air for combustion et a subeatmospherio pressure through one portion of said cooling Zone and delivering said air in another portion of said cooling zone in which it is heated to a predetermined inal temperature at a super-atmospheric pressure.

Signed at Sedgley, near Dudley, Worcester,'Great Britain, this day of July 9th A. D.

vi929.y

y THoMAs TALBOT.

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